How Far Along Am I, Really? Pregnancy Dating FAQs
Finding out you’re pregnant can bring a lot of questions to your mind, and a big one you might ask first is: “How far along am I?”
Gestational age (how many weeks along you are) can be confusing, but it’s a crucial piece of information to have no matter what pregnancy options you’re considering—and it’s important to make sure you’re right, not just guessing.
In this blog, we’ll talk about some frequently asked questions related to gestational age, why gestational age is so important to know, and the best way to get an accurate date. We’ll address a few common concerns and break it all down in a way that’s easy to understand, starting with:
Q: What are the different methods of dating your pregnancy?
Easy first guess: LMP dating is the simplest way to estimate gestational age, and it’s calculated by figuring out how many weeks have passed since the first day of your last menstrual period (LMP). It’s a good first step to get an estimate, but it can be off due to a variety of reasons—like irregular cycles, misremembered periods, and other common factors discussed below—which is why an ultrasound is necessary for a truly accurate date.
Accurate confirmation: A confirmation ultrasound is the best way to date your pregnancy with precision. A sonographer will take measurements of the fetus or embryo to provide you with an accurate gestational age, which is a crucial part of figuring out what pregnancy options are available to you (more on that below).
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Q: How is gestational age determined?
Your gestational age is actually measured from the first day of your last period, not the day you conceived! For instance, if you guess that you conceived about 6 weeks ago, that would mean you’re more like 8 weeks along. Confusing, right? All those dates can start to feel jumbled up, and that’s part of why it’s so important to get an accurate gestational age with an ultrasound, because an ultrasound relies on measurements.
Q: How common is it to misdate your pregnancy?
Using the LMP method, being off by a couple of weeks is very common. Many women incorrectly recall their last period (we’ve all been there!), and irregular cycles, implantation bleeding, and missed periods can also impact accuracy. On the other hand, an ultrasound is extremely accurate in dating a pregnancy because the sonographer takes precise measurements of the embryo or fetus to determine gestational age.
Q: Does it matter if I’m off in my guess?
Being just a week or two off in your guess can impact what pregnancy options are available to you. Your body and the embryo or fetus change quickly and substantially in the first 12 weeks of pregnancy. For example, at 10 weeks gestation the fetus is as long as a strawberry, and just two weeks later it grows to the length of a plum.
Q: Does gestational age matter if I’m considering abortion?
How far along you are especially matters if you’re considering abortion. Gestational age impacts your experience with the abortion pill or surgical abortion—even just a week’s difference can affect pain levels, increase risk factors, and decrease effectiveness. This is especially important if you’re considering the abortion pill, as the FDA has only approved its use up to 10 weeks.
Q: How does my unique menstrual cycle impact pregnancy dating?
Irregularities in your cycle can make guessing based on LMP difficult, because LMP operates under the assumption that you have a standard 28-day cycle where you ovulated on exactly day 14 (which isn’t the case for most people). The length of your cycle, variations from month to month, the exact day you ovulate, and missed periods can all factor into how far along you are. This is why the LMP dating method alone is not a reliable way to confirm gestational age.
Q: What if I use a cycle tracking app?
Cycle tracking apps are a great place to start! Tracking your periods and fertile windows can help give you a better idea of how far along you are. But even if you’re a fastidious tracker, these methods are limited in being able to tell precise gestational age. Most period tracking apps don’t confirm when in your cycle you ovulated, and sometimes implantation bleeding or early pregnancy bleeding can be confused with a period, which can drastically affect how many weeks along you think you are.
Q: How can implantation bleeding and pregnancy bleeding confuse dating?
Implantation bleeding is a common early pregnancy symptom which occurs around the same time you would have had a period if you weren’t pregnant. This can confuse pregnancy dating guesses. Other forms of pregnancy bleeding, both normal and abnormal, can also make LMP dating tricky. It’s not uncommon that we perform an ultrasound and the pregnancy is a month further along than our patient guessed, because they mistook pregnancy-related bleeding for their period.
Q: What if I was on birth control?
LMP dating assumes you have a 28-day period and that you ovulated on day 14, but birth control disrupts ovulation timing. Birth control also affects your bleeding, which can make figuring out your last period confusing. In short, the effects of birth control on your cycle can throw a wrench into the LMP dating method.
Q: What’s the best way to date my pregnancy?
A confirmation ultrasound is the most accurate way to determine gestational age. During a confirmation ultrasound, a sonographer will take measurements of the embryo or fetus and use those to determine how far along you are. This method is based on standard fetal measurements and is extremely precise.
Getting this answer right is your best first step.
If you’re facing an unplanned pregnancy and trying to navigate all the questions that come with it, “how far along am I?” is one that’s worth tackling first. And the best news is, a confirmation ultrasound also checks for the two other crucial things you need to know about your pregnancy! An ultrasound will tell you whether the pregnancy is viable, and whether it’s ectopic (implanted outside the uterus and life-threatening). One ultrasound, three important questions answered.
No matter what pregnancy options you’re considering, an ultrasound is your best first step—because you deserve to make a decision from a place of confidence and clarity.
At Thrive Medical Clinic in Traverse City, Michigan, we offer no-cost ultrasounds and a safe place to process, ask questions, and receive support. Schedule your free appointment below!